Glue and method of making the same



Patented Oct. 8, 1935 UNITED STATES PATENT OFFICE Herbert W. Kelley, Winchester, Mass., assignor to Union Paste Company, Medford, Mass, a copartnership No Drawing. Application December 20, 1933, Serial No. 703,301

2 Claims.

The present invention is concerned with the improvement of adhesives in the form of glues for the purpose of producing such adhesives in a form free from sulphur or sulphur-containing compounds normally tending to contaminate or combine with materials in the presence of the glue. The improvement is of marked utility in the case of animal glues which have many advantageous commercial aspects, but which normally have present therein a variable but nevertheless substantial sulphur content. The invention is also applicable to other sulphur-containing glues such as fish glues and the like.

I have found that by embodying in the liquid glue in course of preparation either a metal or metallic compound having an affinity for sulphur,

the available sulphur content of the glue may be and is progressively converted into a metallic sulphide. At the completion of such a conversion the glue may be used with impunity in the region or in proximity to metals such as silver, which normally exhibit a great afiinity in combination with sulphur without appreciable or noticeable tarnishing of the silver through the formation of the sulphide even after long periods of time.

For virtually all purposes, I have foundthat the combination of the available sulphur content in the glue is best and most effectively promoted by adding to the glue in its liquid form the requisite quantity of silver for combination in the form of a soluble salt such as silver nitrate. In addition to the conversion of the available sulphur which may be effected through the employment of a soluble salt of silver, this conversion may also be produced through the use of silver in the form of the metal (preferably in a finely divided form such as a colloidal state), or in the form of an insoluble compound such as silver oxide.

Due to the simplicity of the operation and the fact that the sulphur appears to be effectively combined in either case, I prefer to treat the liquid glue by the simple addition of the soluble silver nitrate with a thorough mixing for the pur-- pose of adequately contacting all of the sulphur content. In order to insure complete conversion of all sulphur available for tarnishing, I propose to add silver nitrate in excess of the amount necessary to completely combine with the sulphur, leaving an excess of the silver compound present in the finished glue.

To the extent that the unconverted silver com- 5 pound within the glue can contact and convert free sulphur from the air during the use of the glue, it appears to be effective for this purpose. However, this is incidental to and apart from the purpose of the present invention, which is the production of a non-contaminating glue of animal origin or the like, which under normal conditions has a free sulphur content with astrong afiinity for a metallic base such as silver, the conversion of the sulphur into the relatively stable sulphide insuring against the formation of sulphide in the form of a tarnish or stain upon silver articles which may be later used or brought into proximity to the glue, regardless of whether the glue may be employed for joining a package for the reception of the silver, or employed for other purposes which may involve the use of silver in connection therewith.

What is claimed is:

1. The method of preparing a glue of animal origin or the like having an available sulphur content for employment in connection with the packaging of silverware or similar metallic Ware tarnished by the presence of sulphur, which con= sists in permanently adding to liquid glue, a soluble silver salt in excess of the amount necessary to completely combine with all of the available sulphur content present in the glue, and accordingly convert a substantial portion of the silver salt into a resulting stable compound of silver sulphide remaining in the glue.

2. A glue of animal origin or the like stabilized for employment in the packaging of silverware or other tarnishable metallic ware containing a silver sulphide distributed therethrough formed by the conversion of available sulphur originally present in the glue and an additional amount of silver in a form available for conversion into sulphide, and further characterized by a freedom from sulphur available for combination with metals.

HERBERT W. KELLEY. 

